Savvy coders have developed iPhone "skins" that work with most smartphones based on the Windows Mobile and Palm operating systems.

The issue has angered Apple to such an extent that it has sent its lawyers after a number of those involved - both directly and indirectly.

The skins don't add any new functionality to the devices, but make use of the iPhone's copyrighted icons to create a UI that distinctly resembles Apple's hybrid mobile phone.

Soon after the skins were uploaded to the Brighthand and Xda-developers internet message boards, Apple unleashed its legal team, who sent removal letters to at least one of the websites hosting the files.

Apple's lawyers also sent letters to journalists who simply reported on the fact that the skins were available.

"It has come to our attention that you have posted a screenshot of Apple's new iPhone and links that facilitate the installation of that screenshot on a PocketPC device," law firm O'Melveny & Myers LLP wrote to Paul O'Brien, who runs the MoDaCo website.

"While we appreciate your interest in the iPhone, the icons and screenshot displayed on your website are copyrighted by Apple.

"Apple therefore demands that you remove this screenshot from your website and refrain from facilitating the further dissemination of Apple's copyrighted material by removing the link to http://forum.xda-developers.com, where said icons and screenshot are being distributed."

Apple's actions have sparked fury among tech industry watchers, who have accused the company of bullying and being notoriously litigious.

"I think this is all complete nonsense," Michael Arrington, of the influential technology blog TechCrunch, said.

"If Apple wants to go after the guy that made the Windows Mobile skin that looks like the iPhone, fine. But to bully bloggers who are simply reporting on this is another matter."